Hoyeraal-Hreidarsson Syndrome (HHS)

Dyskeratosis congenita (DC) is a bone-marrow failure syndrome characterized by early onset of reticulate skin hyperpigmentation, nail dystrophy, hyperkeratotic palms, hypotrichosis, atresia of the lacrimal ducts, poor dentition, and oral leukoplakia. The progressive bone-marrow failure affects the majority of cases. There is heterogeneity in the severity of the bone-marrow failure as well as in the range of associated anomalies, and an increased risk for a variety of malignancies. Some patients may be initially characterized as having constitutional or idiopathic aplastic anemia or myelodysplastic syndromes. Hoyeraal-Hreidarsson Syndrome is a severe form of X-linked DC with microcephaly, growth and mental retardation, spastic paresis, ataxia and immunodeficiency. In all forms, telomere protection or maintenance is defective.

Tests Available

Forms and Documents

Test Details

  • 1. Confirmation of a clinical diagnosis.
  • 2. Carrier testing for family members of the affected patient
  • 3. Confirmation that a potential hematopoietic stem cell transplant donor is not affected
  • 4. Prenatal diagnosis in at-risk pregnancies


3 weeks
2-5 mL Blood - Lavender Top Tube
Buccal Swabs


  • 284 Aplastic anemia and other bone marrow failure syndromes
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  1. Vulliamy TJ, et al, Mutations in dyskeratosis congenita, Blood 107:2680-2685, 2006
  2. Vulliamy TJ, et al, The RNA component of telomerase is mutated in autosomal dominant dyskeratosis congenital, 2001, Nature 413:432
  3. He J, et al, Targeted disruption of Dkc1, the gene mutated in X-linked dyskeratosis congenital causes embryonic lethality in mice. 2002, Oncogene 21:7740